What Causes Chronic Thick White Vaginal Discharge?

I have had mirena for 3.5 years without issues, but I have been having and odorless, thick white vaginal discharge that sometimes has a very pale yellow tint to it and the discharge only occurs when I urinate and wipe or if I insert my finger into my vaginal vault and scoop some out. I thought it was a yeast infection because I was recently treated for one a couple of months ago and had another dose of diflucan for such, but the discharge is still there. I am approximately a week and a half away from starting my period as well. I haven t been sexually active in a few months and have no vaginal itching, burning with urination, smell or any other symptoms. Help?